Acidity testkit to determine the total acidity of must or wine.

PRINCIPLE : The total amount of acidity = amount of added BLUE INDICATOR VINOFERM (alkaline), necessary to reach the point of neutralization (colour change). This degree of acidity is expressed as tartaric acid.

HOW TO USE : Fill the special measuring cylinder VINOFERM with (filtrated) juice of wine until the mark 0 is reached. Add a couple of ml of BLUE INDICATOR VINOFERM and shake (close the measuring cylinder off with your thumb and turn around). Repeat this, if necessary drop by drop, until the colour changes from dark green to (not quite) blue. This is the point of neutralization. The number ml in the measuring cylinder (wine + blue indicator) gives us the total degree of acidity of the must or wine in grams per liter (7 to 8 gr/l is ideal for wine). With the litmus paper, we check the result : when 1 drop of treated must does not cause a change in colour, de measurement is correct; when the colour changes into red, the liquid is too acid and additional blue indicator has to be added; when the colour changes into blue-violet, it is too alkaline and the test has to be recommenced. For dark red wines, the colour change is hard to see. It has to be diluted to ½ or to 1/3 with distilled water and the result has to be multiplied by 2 or 3. For very acid juices the same is done as the graduation on the measuring cylinder is limited to 20. Corrections on must or Wine : Cider and table-wines (6-10° alk.) should have an acidity of 6-8 gr/l (i.e. an average of 7 gr/). Social wines and dessert wines (13-15° alk.) can have an acidity of 8-10° gr/l (an average of 9 gr/l).
Too little acid : e.g. only 4 gr/l. For a table-wine, add (7-4 =) 3 gr tartaric acid or 3,6 gr lactic acid 80% per liter. For a social or dessert wine, add (9-4 =) 5 gr tartaric acid or 6 gr lactic acid 80% per liter.
Too much acid : e.g. redcurrant juice with 25 gr/l acid. 10 l of this must contains (10x25 =) 250 gr acid and can be used to make (250 : 7 =)36 l table-wine or (250 : 9 =) 28 l dessert wine. Therefore dilution is necessary ! For table-wine, add (36-10 =) 26 l water. For dessert wine, add (28-10 =) 18 l water. Attention : adding water means reducing the density (sugar) : therefore, sugar will have to be added.